Method for processing radio link failure report and method for adjusting mobile parameter

ABSTRACT

A method and a system for processing a Radio Link Failure (RLF) report, where when a User Equipment (UE) encounters an RLF in a first cell controlled by a first evolved base station and selects a second cell controlled by a second evolved base station to re-establish an Radio Resource Connection (RRC), are provided. The method includes sending, by the second evolved base station, the RLF report to every corresponding evolved base station according to the PCI of the first cell having been received from the UE, where the PCI of the first cell, the PCI of a second cell, the CRNTI of the UE in the first cell, and UE authentication information are carried in the RLF report, and authenticating, by every evolved base station the UE according to the UE authentication information. Another method for processing an RLF report, and two methods for adjusting a mobile parameter, are also provided.

PRIORITY

This application is a continuation application of prior application Ser.No. 12/892,072, filed Sep. 28, 2010, which claims the benefit under 35U.S.C. §119(a) of a Chinese patent application filed on Sep. 29, 2009 inthe Chinese Intellectual Property Office and assigned Serial No.200910178593.X, the entire disclosure of which is hereby incorporated byreference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to the field of communicationtechnologies.

More particularly, the present invention relates to a method forprocessing a Radio Link Failure report and a method for adjusting amobile parameter.

2. Background of the Invention

System Architecture Evolution (SAE) is an evolved system structureproposed by the 3^(rd) Generation Partnership Project (3GPP). At aninitial stage of network deployment or during operation of a wholemobile network, a large amount of human labor is required forconfiguring and optimizing a network parameter (particularly for settinga radio parameter), so as to ensure a favorable coverage and capacity,mobile robustness, load balance in mobility, access rate of userequipment, etc. Therefore, a Self-Optimization Network (SON) requirementis proposed in the SAE system. A self-optimization architectureaccording to the related art is as illustrated in FIG. 1.

After being powered up, an evolved base station (evolved Node B, eNB)begins a self-configuration process. As illustrated in FIG. 1, theself-configuration includes: (A) Basic settings and (B) Initial radioparameter configuration. Specifically:

(A) Basic settings include: a-1˜a-4 and the like as illustrated in FIG.1, in which:

a-1 denotes configuring an IP address for the eNB and detecting anOperation, Administration and Maintenance (OAM);

a-2 denotes authentication between the eNB and the network;

a-3 denotes, for a home base station, finding a corresponding gateway;and

a-4 denotes downloading the operation parameter and software of the eNB.

(B) initial radio parameter configuration includes: b-1˜b-2 and the likeas illustrated in FIG. 1, in which:

b-1 denotes configuring a neighbor cell list; and

b-2 denotes configuring a coverage capacity related parameter.

The above self-configuration is performed according to ideal scenariossuch as experience, simulation, and the like. Actual network performancemay vary depending on influences of buildings, climates, surroundingenvironments, etc. Therefore, after the self-configuration is completed,the configuration of many parameters is probably not optimal. In orderto gain better performance for the network so as to meet therequirements of operators and users, the optimization process of thenetwork is very important. At present, self-optimization havingrelatively great importance includes: the self-optimization of theneighbor cell list, the self-optimization of the coverage and capacity,the self-optimization of the mobile robustness, the self-optimization ofthe load balance, the self-optimization of a Random Access Channel(RACH) parameter, power saving, interference reduction, etc.Specifically, the interference reduction may be a part of theself-optimization of the coverage and capacity. In FIG. 1, (C) onlyillustrates a portion of self-optimization operations by taking “c-1:The self-optimization of the neighbor cell list,” and, “c-2: Theself-optimization of the coverage and capacity,” as examples.

In the self-optimization of the mobile robustness, the most importantissue is the way to determine if handover is too late or too early. Inthe self-optimization of the coverage and capacity, another relativelyimportant issue is to determine whether a coverage hole exists.

In existing methods for determining too late handover, determining tooearly handover, and determining if a coverage hole exists, the followingoperation is common. When a User Equipment (UE) encounters Radio LinkFailure (RLF) in a cell 1 controlled by an eNB1 and selects a cell 2controlled by an eNB2 to re-establish a Radio Resource Connection (RRC),the UE sends an RRC re-establishment request message to the eNB2. ThePhysical Cell Identifier (PCI) of the cell 1, the Cell Radio NetworkTemporary Identifier (CRNTI) of the UE in the cell 1, and the shortinformation of Media Access Control used for data Integrity of signalingmessages (short MAC-I) are carried in the RRC re-establishment requestmessage. The eNB2 determines the base station (i.e., the eNB1) thatcontrols the cell corresponding to the PCI according to the PCI, andsends an RLF report to the eNB1. The CRNTI of the UE in the cell 1, thePCI of the cell 1, and the PCI of the cell 2 are carried in the RLFreport.

After receiving the RLF report, the eNB1 based thereon determineswhether too late handover and/or too early handover have occurred, ordetermines whether a coverage hole exists.

The operation in common for the above three methods actually relates toa processing manner for the RLF report. The above existing processingmanner for the RLF report has a problem in that, after the eNB2 receivesthe RRC re-establishment request message from the UE, if there are twoor more adjacent cells (e.g. controlled by the eNB1 and an eNB3,respectively) having the same PCI, the eNB2 may be incapable ofdetermining the eNB to which the RLF report should be sent. In case oferroneous sending, the eNB may be caused to make a wrong determination,thus leading to an adverse influence on network performance. Thisproblem also occurs in other processes that need to perform theself-optimization based on the RLF report.

The self-optimization of the mobile load balance seeks to ensure theload balance between adjacent cells or between cells having overlappedcoverage, or to transfer a part of the load contained in a congestedcell to an adjacent cell or a cell having overlapped coverage. This maybe implemented by switching the UE or by adjusting the mobile parameter.The mobile parameter includes a cell switching parameter and a cellre-selection parameter. In order to avoid a ping-pong effect resultingfrom UE switching, a cell needs to negotiate with the adjacent cell whenadjusting its mobile parameter. How to ensure a cell adjusts the mobileparameter with all its adjacent cells in a harmonious manner is aproblem to be addressed at present.

The occurrence of the above problem causes degradation of theself-optimization effect, and the network performance cannot be ensuredeffectively.

Therefore, a need exists for a method and system for processing an RLFreport and for adjusting a mobile parameter, so as to enhance theself-optimization effect, thus to improve network performance.

SUMMARY OF THE INVENTION

An aspect of the present invention is to address at least theabove-mentioned problems and/or disadvantages and to provide at leastthe advantages described below. Accordingly, an aspect of the presentinvention is to provide a method for processing a Radio Link Failure(RLF) report, so as to enhance the self-optimization effect, thus toimprove the network performance.

Another object of the present invention is to provide a method foradjusting a mobile parameter, so as to enhance the self-optimizationeffect, thus to improve the network performance.

In accordance with an aspect of the present invention, a method forprocessing an RLF report when a User Equipment (UE) encounters an RLF ina first cell controlled by a first evolved base station and selects asecond cell controlled by a second evolved base station to re-establisha Radio Resource Connection (RRC), is provided. The method includesreceiving, by the second evolved base station, an RRC re-establishmentrequest message sent from the UE, wherein a Physical Cell Identifier(PCI) of the first cell, a Cell Radio Network Temporary Identifier(CRNTI) of the UE in the first cell, and short information of MediaAccess Control used for data Integrity of signaling messages (shortMAC-I) are carried in the RRC re-establishment request message, sending,by the second evolved base station, the RLF report to every evolved basestation that respectively controls a corresponding cell, according tothe PCI of the first cell, wherein the PCI of the first cell, the CRNTIof the UE in the first cell, and UE authentication information used forauthenticating the UE are carried in the RLF report, and authenticating,by every evolved base station that receives the RLF report, the UEaccording to the UE authentication information carried in the RLFreport.

In accordance with another aspect of the present invention, a method forprocessing a Radio Link Failure RLF report, when a User Equipment UEencounters an RLF in a first cell controlled by a first evolved basestation and selects a second cell controlled by a second evolved basestation to re-establish a Radio Resource Connection RRC, is provided.The method includes receiving, by the second evolved base station,information sent from the UE including a PCI of the first cell, a CRNTIof the UE in the first cell, short MAC-I, and cell first authenticationinformation used for authenticating a cell, and sending, by the secondevolved base station, the RLF report to an evolved base station thatcontrols the corresponding cell, according to the cell firstauthentication information.

In accordance with yet another aspect of the present invention, a methodfor adjusting a mobile parameter, when a first evolved base stationwhich determines to adjust the mobile parameter of its controlled cell,is provided. The method includes sending, by the first evolved basestation, a mobile parameter adjustment request message to every evolvedbase station that controls a respective one of all cells subjected tothe adjustment, wherein the adjusted mobile parameter is carried in themobile parameter adjustment request message; receiving, by the firstevolved base station, a mobile parameter adjustment acceptance messageor a mobile parameter adjustment refusal message returned from eachevolved base station, if each of the evolved base station returns themobile parameter adjustment acceptance message, then adjusting, by thefirst evolved base station, the mobile parameter, and sending a mobileparameter adjustment acknowledgement message to every evolved basestation, and, if at least one of the evolved base station returns themobile parameter adjustment refusal message, then not adjusting, by thefirst evolved base station, the mobile parameter, and sending a mobileparameter adjustment cancellation message to every evolved base station.

In accordance with an aspect of the present invention, a method foradjusting a mobile parameter, when a first evolved base stationdetermines to adjust the mobile parameter of its controlled cell, isprovided. The method includes receiving, by every evolved base stationthat controls a respective one of all cells subjected to the adjustment,a mobile parameter adjustment request message from the first evolvedbase station, wherein the adjusted mobile parameter is carried in themobile parameter adjustment request message, determining, by everyevolved base station respectively, whether the adjustment is accepted,and if so, returning a mobile parameter adjustment acceptance message tothe first evolved base station, and, if not, returning a mobileparameter adjustment refusal message to the first evolved base station,if receiving a mobile parameter adjustment acknowledgement message fromthe first evolved base station, then replacing, by every evolved basestation respectively, the parameter related to the mobile parameter ofthe controlled cell of the first evolved base station that is storedcurrently by the adjusted mobile parameter, and, if receiving a mobileparameter adjustment cancellation message from the first evolved basestation, then retaining unchanged, by every evolved base station, theparameter related to the mobile parameter of the controlled cell of thefirst evolved base station that is stored currently.

As can be seen from the above technical solution, in an exemplary methodfor processing an RLF report, when the UE encounters the RLF in thefirst cell controlled by the first evolved base station and selects thesecond cell controlled by the second evolved base station tore-establish a radio link, the authentication is performed for the UE orthe cell in which the UE encounters the RLF by sending theauthentication information. Thus, even when there are two or moreadjacent cells having the same PCI, the cell in which the UE encountersthe RLF can be determined correctly, thus enhancing theself-optimization effect, and improving the network performance.

In the exemplary method for adjusting a mobile parameter, the evolvedbase station that initiates the mobile parameter adjustment performsdetermination in a collective manner according to the message returnedfrom every relative evolved base station that indicates accepting orrefusing the mobile parameter adjustment, and sends the message thatindicates adjusting or not the related mobile parameter to everyrelative evolved base station in a collective manner according to theresult of the determination. Finally, all evolved base stations adjustor not the related mobile parameter, thus avoiding the problem that themobile parameters stored in respective evolved base stations areinconsistent with each other, ensuring that a cell adjusts the mobileparameter with all its adjacent cells in a harmonious manner, enhancingthe self-optimization effect, and improving the network performance.

Other aspects, advantages, and salient features of the invention willbecome apparent to those skilled in the art from the following detaileddescription, which, taken in conjunction with the annexed drawings,discloses exemplary embodiments of the invention.

BRIEF DESCRIPTION OF THE DRAWINGS

The above and other aspects, features, and advantages of certainexemplary embodiments of the present invention will be more apparentfrom the following description taken in conjunction with theaccompanying drawings, in which:

FIG. 1 is a schematic diagram illustrating a basic self-optimizationarchitecture in an existing System Architecture Evolution (SAE) systemaccording to the related art;

FIG. 2 is a schematic diagram illustrating a method for processing aRadio Link Failure (RLF) report according to an exemplary embodiment ofthe present invention;

FIG. 3 is a schematic diagram illustrating a method for processing anRLF report according to an exemplary embodiment of the presentinvention; and

FIG. 4 is a schematic diagram illustrating a method for adjusting amobile parameter according to an exemplary embodiment of the presentinvention.

Throughout the drawings, it should be noted that like reference numbersare used to depict the same or similar elements, features, andstructures.

DETAILED DESCRIPTION OF EXEMPLARY EMBODIMENTS

The following description with reference to the accompanying drawings isprovided to assist in a comprehensive understanding of exemplaryembodiments of the invention as defined by the claims and theirequivalents. It includes various specific details to assist in thatunderstanding but these are to be regarded as merely exemplary.Accordingly, those of ordinary skill in the art will recognize thatvarious changes and modifications of the embodiments described hereincan be made without departing from the scope and spirit of theinvention. In addition, descriptions of well-known functions andconstructions may be omitted for clarity and conciseness.

The terms and words used in the following description and claims are notlimited to the bibliographical meanings, but, are merely used by theinventor to enable a clear and consistent understanding of theinvention. Accordingly, it should be apparent to those skilled in theart that the following description of exemplary embodiments of thepresent invention is provided for illustration purpose only and not forthe purpose of limiting the invention as defined by the appended claimsand their equivalents.

It is to be understood that the singular forms “a,” “an,” and “the”include plural referents unless the context clearly dictates otherwise.Thus, for example, reference to “a component surface” includes referenceto one or more of such surfaces.

The present invention proposes a method for processing a Radio LinkFailure (RLF) report and a method for adjusting a mobile parameter withrespect to the problem presented in the existing self-optimizationprocess.

In an exemplary implementation, when a User Equipment (UE) encountersthe RLF in the first cell controlled by the evolved base station andselects the second cell controlled by the second evolved base station tore-establish a radio link, the authentication is performed for the UE orthe cell in which the UE encounters the RLF by sending theauthentication information. Thus, even when there are two or moreneighbor cells having the same Physical Cell Identifier (PCI), the cellin which the UE encounters the RLF can be determined correctly, thusenhancing the self-optimization effect, and improving the networkperformance.

Exemplary embodiments of the present invention include two methods forprocessing an RLF report, which are respectively described in moredetail below with reference to the accompanying drawings.

FIG. 2 is a schematic diagram illustrating a method for processing anRLF report according to an exemplary embodiment of the presentinvention.

Referring to FIG. 2, an exemplary method includes the following process.

In step 201, the UE encounters the RLF in the cell 1, assuming for thisexample that the cell 1 is controlled by evolved base station (evolvedNode B, eNB)1.

In step 202, the UE performs cell re-selection, and selects the cell 2to re-establish the Radio Resource Connection (RRC), assuming for thisexample that the cell 2 is controlled by eNB2.

In step 203, the UE sends an RRC re-establishment request message to theeNB2. The PCI of the cell 1, the Cell Radio Network Temporary Identifier(CRNTI) of the UE in the cell 1, and the short information of MediaAccess Control used for data Integrity of signaling messages (shortMAC-I) are carried in the RRC re-establishment request message.

Here, the short MAC-I is the 16 least significant bits of the MAC-I. TheMAC-I is obtained by performing calculation from the PCI of the cell 1,the CRNTI of the UE in the first cell, the identifier ECI of the cell 2,and the security related parameter of the cell 1. Specifically, the ECIis the unique cell identifier of the cell in a Public Land MobileNetwork (PLMN). The ECI refers to the Evolved Universal TerrestrialRadio Access Network Cell Identifier (Evolved UTRAN Cell Identifier).

In step 204, the eNB2 determines all cells corresponding to the PCIaccording to the said PCI, and determines every evolved base stationthat controls a respective one of all the cells.

As described above, in the neighbor cells of the cell 2, there may betwo or more neighbor cells having the same PCI, thus two or more cellsmay be found according to the said PCI. These cells may be controlled bydifferent evolved base stations. This step seeks to find those evolvedbase stations. Assume for this example that they are the eNB1 and theeNB3. In the case that only one eNB is found, the method of the presentinvention is also applicable.

In step 205, the eNB2 sends an RLF report to every evolved base stationdetermined in step 204. In addition to the PCI of the cell 1, the PCI ofthe cell 2 and the CRNTI of the UE in the cell 1, UE authenticationinformation used for authenticating the UE is also carried in the RLFreport.

According to the assumption of step 204, in this step, the eNB2 may sendthe RLF report to the eNB1 and the eNB3. The PCI of the cell 1 and theCRNTI of the UE in the cell 1 being carried in the RLF report are usedfor determining the context of the UE, and the UE authenticationinformation carried in the RLF report is used for determining whetherthe context of the UE is the context of such UE encountering the RLF.

In this step, the UE authentication information being carried in the RLFreport can be any information capable of determining whether the contextof a certain UE is the context of such UE encountering the RLF, e.g. maybe the ECI of the cell 2 as well as the short MAC-I contained in the RRCre-establishment request message received by the cell 2 from the UE, oralternatively, may be the Enhanced Cell Global Identifier (ECGI) of thecell 2 as well as the short MAC-I contained in the RRC re-establishmentrequest message received by the cell 2 from the UE, or alternatively,may be the short MAC-I contained in the RRC re-establishment requestmessage received by the cell 2 from the UE (in this case, the shortMAC-I may be combined with the PCI of the cell 2 being contained in theRLF report to perform the authentication for the UE).

In step 206, every evolved base station that receives the RLF reportauthenticates the UE according to the UE authentication informationcarried in the RLF report.

More specifically, every evolved base station (which in this exampleincludes the eNB1 and the eNB3) that receives the RLF report may firstdetermine the context of the UE according to the PCI of the first celland the CRNTI of the UE in the first cell being carried in the RLFreport, and determine whether the context of the UE is the context ofthat UE encountering the RLF according to the UE authenticationinformation. If so, the procedure proceeds to step 207. Otherwise, themessage may be discarded without any processing.

In this step, an exemplary method to determine the context of the UEaccording to the PCI of the cell 1 and the CRNTI of the UE in the firstcell may include the following process.

First, every eNB that receives the RLF report finds the correspondingcell according to the PCI.

According to the above description, the cell having the same PCI may bepresent in different eNBs, and also in the same eNB. Therefore, theremay be two or more cells found. Herein, these cells are collectivelyreferred to as a cell x.

Then, the context of the UE is found according to the CRNTI in the cellx.

If finding two or more cells, the eNB that receives the RLF report mayalso determine whether the context of the corresponding UE is stored inthe cell to further determine whether the found cell is the cell inwhich the UE encounters the RLF.

In this step, exemplary methods of determining whether the context ofthe UE is the context of that UE encountering the RLF may vary dependingon different UE authentication information.

If the UE authentication information is the ECI of the cell 2 and theshort MAC-I being contained in the RRC re-establishment request message,the way for determination is as follows: Every eNB that receives the RLFreport calculates the MAC-I from the security related parameter of thecell x, as well as the cell 2 identity ECI, the CRNTI of the UE in thefirst cell, and the PCI of cell 1 being contained in the RLF report. The16 least significant bits of the MAC-I are compared with the short MAC-Icontained in the RLF report. If they are the same as each other, it isdetermined that the context of the UE having been found is the contextof the UE encountering the RLF. Otherwise, it is determined that it isnot the context of the UE encountering the RLF.

If the UE authentication information is the ECGI of the cell 2 and theshort MAC-I being contained in the RRC re-establishment request message,the way for determination is as follows: Every eNB that receives the RLFreport first obtains the ECI of the cell 2 according to the ECGI of thecell 2, and then authenticates whether the context of the UE having beenfound is the context of the UE encountering the RLF according to theabove “short MAC-I+the ECI of the cell 2” manner.

If the UE authentication information is the short MAC-I contained in theRRC re-establishment request message, the way for determination is asfollows: Every eNB that receives the RLF report first finds the ECI ofthe cell 2 from the neighbor cell list according to the PCI of the cell2 being contained in the RLF report, and then authenticates whether thecontext of the UE having been found is the context of the UEencountering the RLF according to the above “short MAC-I+the ECI of thecell 2” manner.

Based on the determination of this step, whether the cell controlled bythis evolved base station is the cell in which the UE encounters the RLFmay be determined. At this time, the eNB1 may execute step 207.

In step 207, the eNB1 performs corresponding self-optimizationprocessing according to the RLF report.

In this step, the eNB1 may determine the reason of the RLF according tothe RLF report and other corresponding information, and determine basedon this whether the too early handover, the too late handover, thecoverage hole, and the like are presented. Since the subsequentoperation for performing self-optimization processing is not anessential point for the present invention, the description thereof isomitted herein, and only a brief description is provided below.

Regarding the method of determining the too early handover, the eNBwhere the UE encounters the RLF may determine whether a UE contextrelease request message is sent to the cell 2 controlled by the eNB2 torelease the context of the UE within a certain time. If so, the eNBdetermines that the too early handover was performed, and thus sends atoo early handover indication to the eNB2.

In order to assist the network in determining either too late handoveror the coverage hole, the UE needs to report other information to thenetwork. For example, the UE reports the position of the UE at the timethat the RLF is presented, as well as the measurement result of otherneighbor cells, to the eNB2. These may be reported through the RRCre-establishment request message or an RRC re-establishment completionmessage or another RRC message. Thus, the eNB where the UE encountersthe RLF may determine either too late handover or the coverage hole,according to the position at the time that the RLF is presented, as wellas the measurement result from the UE. For example, if the signal of thecell 1 has been very weak, and the signal of the cell 2 is sufficientlystrong when the UE encounters the RLF, the determination at this timeshould result in the too late handover. If the signals of both the cell1 and the cell 2 are very weak when the UE encounters the RLF, thedetermination may be the coverage hole.

At this point, the method for processing the RLF report according to thefirst exemplary embodiment of the present invention is completed.

FIG. 3 is a schematic diagram illustrating a method for processing anRLF report according to an exemplary embodiment of the presentinvention.

Referring to FIG. 3, an exemplary method includes the following process.

In step 301, the UE encounters the RLF in the cell 1, assuming for thisexample that the cell 1 is controlled by the eNB1.

In step 302, the UE performs cell re-selection, and selects the cell 2to re-establish the RRC, assuming for this example that the cell 2 iscontrolled by the eNB2.

In step 303, the UE sends the following information to the eNB2: the PCIof the cell 1, the CRNTI of the UE in the cell 1, the short MAC-I, andcell first authentication information used for authenticating the cell.

Here, the information of this step may be carried by the RRCre-establishment request message, the RRC re-establishment completionmessage, or another RRC message, so as to send the same to the eNB2, inso far as the above information can be carried in the RRC message. Theinformation of this step may be sent from the UE to the eNB2 through oneor more RRC messages.

In this step, the cell first authentication information carried in theRRC message may be any information capable of accurately determiningwhether a certain cell is the cell in which the UE encounters the RLF,e.g., may be the ECGI of the cell 1 and/or the frequency of the cell 1.Specifically, the ECGI may uniquely identify a certain cell. On thebasis of a favorable network plan, there is almost never a cell havingboth the same frequency and the same PCI as another cell. Therefore, thecombination of the frequency and the PCI may also uniquely identify acertain cell.

In step 304, the eNB2 determines the corresponding cell according to thecell authentication information.

For example, if the cell authentication information contains the ECGI,the corresponding cell may be uniquely determined according to the ECGI.If the cell authentication information contains the frequency of thecell in which the UE encounters the RLF, on the basis of a favorablenetwork plan, the corresponding cell may be determined according to thePCI and the frequency.

To sum up, in this step, the cell in which the UE encounters the RLF maybe uniquely determined according to the cell authentication information.

In step 305, the eNB2 sends the RLF report to the eNB1.

Here, the information carried in the RLF report may be classified intothe following cases.

First case: Assuming for this example that the PCI of all cellscontained in the eNB1 are different from each other, the cell in whichthe UE encounters the RLF may be uniquely determined according to thePCI carried in the RLF report. Therefore, the PCI of the cell 1, the PCIof the cell 2, and the CRNTI of the UE in the first cell are carried inthe RLF report.

Second case: Assuming for this example that there is a cell having thesame PCI as another, this means that the cell in which the UE encountersthe RLF cannot be uniquely determined according to the PCI carried inthe RLF report. At this time, in addition to the PCI of the cell 1, thePCI of the cell 2 and the CRNTI of the UE in the first cell, second cellauthentication information used for authenticating the cell may also becarried in the RLF report, for the eNB1 to determine the cell in whichthe UE encounters the RLF. The second cell authentication informationmay include the ECGI of the cell 1 and/or the frequency of the cell 1.

In this case, an exemplary method for the eNB1 to determine the cell inwhich the UE encounters the RLF according to the information carried inthe RLF report may include the following process.

The eNB1 determines the corresponding cell according to the PCI of thecell 1 being carried in the RLF report. If there are two or more cellshaving the same PCI, the cell in the two or more cells having the samePCI whose ECGI is equal to such ECGI is determined as the cell in whichthe UE encounters the RLF, or alternatively, the cell in the two or morecells having the same PCI whose frequency is equal to such frequency isdetermined as the cell in which the UE encounters the RLF.

Alternatively, if the cell second authentication information is the ECGIof the cell 1, the eNB1 that receives the RLF report may directly findthe cell in which the UE encounters the RLF according to the ECGI of thecell 1, i.e., the process of finding the cell in which the UE encountersthe RLF using the PCI of the cell 1 may be omitted.

Of course, there may be other ways in practical applications, in so faras the cell in which the UE encounters the RLF is found according to theinformation carried in the RLF report.

Third case: In order to allow the eNB that receives the RLF report to beable to further authenticate the UE, in addition to the PCI of the cell1, the PCI of the cell 2, and the CRNTI of the UE in the cell 1, UEauthentication information used for authenticating the UE may also becarried in the RLF report sent in this step. As in step 205, the PCI ofthe cell 1 and the CRNTI of the UE in the cell 1 being carried in theRLF report are used for determining the context of the UE, and the UEauthentication information carried in the RLF report is used fordetermining whether the context of the UE is the context of such UEencountering the RLF. Specifically, the UE authentication informationmay include the following:

The ECI of the cell 2 as well as the short MAC-I having been received bya second evolved base station from the UE.

Alternatively, the ECGI of the cell 2 as well as the short MAC-I havingbeen received by a second evolved base station from the UE.

Alternatively, the short MAC-I having been received by a second evolvedbase station from the UE.

The way to determine whether the context of the UE is the context ofthat UE encountering the RLF is the same as the corresponding way fordetermination as described in step 206 illustrated in FIG. 2, and thedescription thereof is omitted herein.

In specific implementation, the above three cases may occursimultaneously, i.e. the cell second authentication information and theUE authentication information may be carried at the same time in the RLFreport.

In step 306, the eNB1 performs corresponding self-optimizationprocessing according to the RLF report.

In this step, the eNB1 may determine the reason of the RLF according tothe RLF report and other corresponding information, and determine basedon this whether too early handover, too late handover, the coveragehole, and the like are presented. The subsequent operation forperforming self-optimization processing is not an essential point forthe present invention and has been described briefly in step 207, thusthe description thereof is omitted herein.

At this point, the method for processing the RLF report according to theexemplary embodiment of the present invention is completed.

In addition to the self-optimization support by processing the RLFreport, a method for adjusting a mobile parameter is also proposed inthe present invention. The method is described in more detail below withreference to the accompanying drawings.

FIG. 4 is a schematic diagram illustrating a method for adjusting amobile parameter according to the present invention.

Referring to FIG. 4, in step 401, the eNB1 determines to adjust themobile parameter of its controlled cell.

In this step, the mobile parameter includes a cell switching parameterand a cell re-selection parameter. The procedure as illustrated in FIG.4 may be executed no matter which of the following the eNB1 decides toadjust: the cell switching parameter, or the cell re-selectionparameter, or both the cell switching parameter and the cellre-selection parameter, of its controlled cell.

In step 402, the eNB1 sends a mobile parameter adjustment requestmessage to every eNB that controls a respective one of all the cellssubjected to the adjustment. The adjusted mobile parameter is carried inthe mobile parameter adjustment request message. Optionally, the currentmobile parameter may also be carried in the mobile parameter adjustmentrequest message.

In this step, assume for this example that the eNB2 and the eNB3 are theeNBs that control a respective one of the cells subjected to theadjustment.

In step 403, the eNB2 and the eNB3 determine whether the adjustment ofthe eNB1 may be accepted.

In this step, the eNB2 and the eNB3 may further determine whether it isrequired to adjust the mobile parameter for its controlled cell afterthe adjustment of the eNB1 is accepted.

In step 404, if the adjustment of the eNB1 may be accepted, the eNB2 andthe eNB3 respectively return a mobile parameter adjustment acceptancemessage to the eNB1.

If the adjustment of the eNB1 cannot be accepted, the eNB2 and the eNB3respectively return a mobile parameter adjustment refusal message to theeNB1 in this step. If the mobile parameter adjustment refusal message isreturned, information representing a refusal reason may be furthercarried in the message, for the eNB1 to perform correspondingprocessing.

The two functions of mobile parameter adjustment acceptance and mobileparameter adjustment refusal may also be implemented by a single message(a mobile parameter adjustment response message). Corresponding to thismethod, information representing acceptance or information representingrefusal may be contained in the mobile parameter adjustment responsemessage, to notify the eNB1 of either accepting or refusing the mobileparameter adjustment request. In the case of refusal, informationrepresenting a refusal reason may be further carried.

In step 405, if both the eNB2 and the eNB3 return mobile parameteradjustment acceptance, the eNB1 adjusts the related mobile parameter,and returns a mobile parameter adjustment acknowledgement message to theeNB2 and the eNB3.

If at least one of the eNB2 and the eNB3 returns mobile parameteradjustment refusal to the eNB1, in this step, the eNB1 does not adjustthe related mobile parameter and return a mobile parameter adjustmentcancellation message to the eNB2 and the eNB3.

In step 406, after receiving the mobile parameter adjustmentacknowledgement message from the eNB1, the eNB2 and the eNB3respectively replace the related mobile parameter corresponding to thecontrolled cell of the eNB1 that is stored currently by the adjustedmobile parameter.

If receiving the mobile parameter adjustment cancellation message fromthe eNB1 in this step, the eNB2 and the eNB3 retain unchanged the mobileparameter stored currently.

At this point, the method for adjusting the mobile parameter accordingto the present invention is completed.

As can be seen from the above exemplary embodiment, when the UEencounters the RLF in the first cell controlled by the first evolvedbase station and selects the second cell controlled by the secondevolved base station to re-establish a radio link, the authentication isperformed for the UE or the cell in which the UE encounters the RLF bysending the authentication information. Thus, even when there are two ormore neighbor cells having the same PCI, the cell in which the UEencounters the RLF can be determined correctly, thus enhancing theself-optimization effect, and improving the network performance.

In an exemplary method for adjusting a mobile parameter, the evolvedbase station that initiates the mobile parameter adjustment performsdetermination in a collective manner according to the message returnedfrom every relative evolved base station that indicates accepting orrefusing the mobile parameter adjustment, and sends the message thatindicates adjusting or not the related mobile parameter to everyrelative evolved base station in a collective manner according theresult of the determination. Finally, all evolved base stations adjustor not the related mobile parameter, thus avoiding the problem that themobile parameters stored in respective evolved base stations areinconsistent with each other, ensuring that a cell adjusts the mobileparameter with all its adjacent cells in a harmonious manner, enhancingthe self-optimization effect, and improving the network performance.

While the invention has been shown and described with reference tocertain exemplary embodiments thereof, it will be understood by thoseskilled in the art that various changes in form and details may be madetherein without departing from the spirit and the scope of the inventionas defined by the appending claims and their equivalents.

What is claimed is:
 1. An apparatus for a wireless communication, theapparatus comprising: a transceiver configured to transmit and receivesignals; and a controller configured to control the transceiver toreceive a radio resource connection (RRC) re-establishment requestmessage from a user equipment (UE), the RRC re-establishment requestmessage comprising a physical cell identifier (PCI) of a first cell, acell radio network temporary identifier (CRNTI) of the UE in the firstcell and short media access control information, wherein the UE haveencountered a radio link failure (RLF) in the first cell, and transmitan RLF report to at least one evolved base station based on the PCI, theRLF report comprising the PCI, the CRNTI, the short media access controlinformation and an enhanced cell global identifier (ECGI) of a secondcell where radio link re-establishment attempt is made, wherein theshort media access control information is obtained based on a securityrelated parameter of the first cell.
 2. The apparatus of claim 1,wherein the short media access control information is a short MAC-I. 3.The apparatus of claim 1, wherein the at least one evolved base stationthat receives the RLF report authenticates the UE according to the shortmedia access control information carried in the RLF report.
 4. Theapparatus of claim 1, wherein the RLF report is transmitted to theevolved base station that respectively controls a corresponding cell,according to the PCI of the first cell.
 5. The apparatus of claim 2,wherein the short MAC-I comprises 16 least significant bits of a MAC-I,and the MAC-I is obtained by performing a calculation from an identifierof the second cell and the security related parameter of the first cell.6. An apparatus for a wireless communication, the apparatus comprising:a transceiver configured to transmit and receive signals; and acontroller configured to control to the transceiver to transmit a radioresource connection (RRC) re-establishment request message to a secondevolved base station, the RRC re-establishment request messagecomprising a physical cell identifier (PCI) of a first cell, a cellradio network temporary identifier (CRNTI) of the UE in the first cell,and short media access control information, wherein the UE haveencountered a radio link failure (RLF) in the first cell, wherein an RLFreport is transmitted from the second evolved base station to at leastone evolved base station based on the PCI, the RLF report comprising thePCI, the CRNTI, an enhanced cell global identifier (ECGI) of a secondcell where radio link re-establishment attempt is made, and the shortmedia access control information, and wherein the short media accesscontrol information is obtained based on a security related parameter ofthe first cell.
 7. The apparatus of claim 6, wherein the short mediaaccess control information is a short MAC-I.
 8. The apparatus of claim6, wherein the at least one evolved base station that receives the RLFreport authenticates the UE according to the short media access controlinformation carried in the RLF report.
 9. The apparatus of claim 6,wherein the RLF report is transmitted to the evolved base station thatrespectively controls a corresponding cell, according to the PCI of thefirst cell.
 10. The apparatus of claim 7, wherein the short MAC-Icomprises 16 least significant bits of a MAC-I, and the MAC-I isobtained by performing a calculation from an identifier of the secondcell and the security related parameter of the first cell.
 11. Anapparatus for a wireless communication, the apparatus comprising: atransceiver configured to transmit and receive signals; and a controllerconfigured to control to the transceiver to receive a radio link failure(RLF) report from the second evolved base station, the RLF reportcomprising a physical cell identifier (PCI) of a first cell, a cellradio network temporary identifier (CRNTI) of a user equipment (UE) inthe first cell, an enhanced cell global identifier (ECGI) of a secondcell where radio link re-establishment attempt is made, and a shortmedia access control information, wherein the second evolved basestation receives a radio resource connection (RRC) re-establishmentrequest message from the user equipment, the RRC re-establishmentrequest message comprising the PCI, the CRNTI and the short media accesscontrol information, wherein the UE have encountered a radio linkfailure (RLF) in the first cell, and wherein the short media accesscontrol information is obtained based on a security related parameter ofthe first cell.
 12. The apparatus of claim 11, wherein the short mediaaccess control information is a short MAC-I.
 13. The apparatus of claim11, wherein the controller is further configured to control toauthenticate the UE according to the short media access controlinformation carried in the RLF report.
 14. The apparatus of claim 11,wherein the RLF report is transmitted to the evolved base station thatrespectively controls a corresponding cell, according to the PCI of thefirst cell.
 15. The apparatus of claim 12, wherein the short MAC-Icomprises 16 least significant bits of a MAC-I, and the MAC-I isobtained by performing a calculation from an identifier of the secondcell and the security related parameter of the first cell.